Okay I've seen posts on here for racing where the technical discussions creates swirls of fog in my head so I know I am at the right place to get some good advice. The thing is it sounds like everyone has their expertise in drags, now I want to see if anyone is experienced at fuel mileage. I have a 97 sx 700 yamaha and I have added the bender triple pipes, v-force reeds and reed spacers, also the bender clutch kit they recommend for this application. Also the jet kit to tune this application. With this clutch helix I had the settings of 60Deg. of twist for racing or 70 deg of twist for trails in the secondary. Plus a shim for the front primary spring. First I put it the way they recommended,(shim in primary and 60deg of twist in the secondary), seemed to run good but engagement RPMS ran a little high it seemed 500-600 more than before. I took out the primary shim and it woke the sled right up and tried to pull my arms off (well almost). So I presumed this was a plus, also was running against a friends sled so I could judge improvements. Next I had a rich condition while trail riding and getting 6 MPG and fouling plugs so spent a day getting the jetting right. No more fouling plugs and MPG went up to 8. Tried the 70 degree setting for trails and was able to get around 10 plus or minus .5 MPG depending on the trail. Threw the stock setup in just to see if I wasted money or not and no-matter what I did it would only get 7-8 and you could tell the performance wasn't there, so I put the bender back in at 70 deg with no shim in the primary and was back to my 10 MPG. The reason I'm looking at this is I love the performance but miss the 12.5 MPG that it was when it was stock, but stock is not my style and I realize that you can't have the best of both worlds but I want to be close. My riding buddy has a new F7 and I have to have mine hopped up so I can keep up with him so his head doesn't get too big, but when he's getting 15 MPG with the F7 and mine was getting8-9 That was just the kicker for me . anyway I just want to keep as much performance as possible but have the clutching set as good as I can for milage without blowing a ton of cash. Maybe I am good as I can expect,,,I dunno but was thinking that adding 10 more degrees of twist helped drastically would going from 70 deg to 80 deg help more? What would be the downfall...Any recommendations would be appreciated. I've only been playing with sleds on the performance end for 2 years now and I think I am starting to get some of the clutching principles learned but when I read the posts on here I feel like a confused young child,,,hahaha. Anyway let me know Thanks Steve

60 deg
no shim
8 MPG

70 deg
no shim
10 MPG

was thinking that adding 10 more degrees of twist helped drastically...
...would going from 70 deg to 80 deg help more?



I would do a temperature test. Go and run the sled as you normally do on 60, then after you get to a part of the exercise where you are running it hard...Stop the sled and check the secondary temperature.
Perform the same exercise at 70 deg and check temperature.
Perform the same exercise at 80 deg and check temperature.

What does the sled feel like by the seat of the pants [how does it perform] and try to relate the temperature to your performance.
You already know the mileage for 60 & 70, so get more information with these "60 & 70" settings to find out other details of how the system is working.
Mebbe you can predict what 80 will do for you.

you want gas milage but your all piped up?!?!
i think gearing would help milage also.

First, what type of temperature am I looking for? I remember reading something on another site and if i recall the secondary was warm to the touch but not hot when I went to 70 deg of twist on the secondary, can't remember how it was at 60 deg of twist. Second , yes triple piped and looking for milage I know I can't have horsepower and mileage together in the same package BUT I do know that you can either optimise power performance for short distances such as drags or for mileage. I have been associated around drag racing for years and if it is powered you can optimise your power to your needs, mine are not for 600 foot drags but for trail, with a little playing around on top end on the lakes and fields. Thanks,,Steve

sno nutz]...First, what temperature am I looking for?

http://www.snowmobileworld.com/forum/index...opic=26194&st=0 (http://www.snowmobileworld.com/forum/index.php?showtopic=26194&st=0)
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From messing around with a few very stout 600's and a 700, I don't see any reason why you can't get 120 deg. or less for the riding you want to do.

sno nutz]...Second, yes triple piped and looking for mileage I know I can't have horsepower and mileage together in the same package BUT...

I disagree. I think if you use a helix that has the "required" angles to match your power capacity at whatever speed you are going or how you are driving...you can get good mileage.
When you throw the weight to it to go extremely short distance, it will haul a$s.

I would like to know what the stock helix was for your 97 sx 700 sled originally.

you can also get better millage in the efficiency of the complete drive system, not only the clutches.....try gearing up a bit, check the drive bearings ,all the bearings in the skid, even add some idlers for less drag.....lots of studs could also take away gas millage...... :)